Due to a recent health boom, various dieting methods for an obesity resolution appear and go off, and topics are not exhausted. It implies that there are no universal dieting methods which are effective for everybody, and that there is a need for providing custom-made dieting methods that are suitable for individuals. A principle of the dieting is simple. Namely, when burned calories are greater than consumed calories, body weight is reduced. In other words, what is important for dieting is a proper meal which is suitable for an individual, and further a combination of the proper meal which is suitable for the individual and exercise (cf. “Exercise and Physical Activity Guide for Health Promotion 2006—To Prevent Lifestyle-related Diseases—<Exercise Guide 2006>,” prepared by the Ministry of Health, Labour and Welfare of Japan, for example).
Regarding the meal, it has been known that not only reducing the consumed calories, but also taking the meal at proper timing, not in accordance with a clock, are effective for the dieting. Namely, it has been known that taking the meal during fasting is effective for the dieting. Although a brain can detect whether it is fasting, feelings of hunger/fullness are subjective, and it has been known that the feelings of hunger/fullness do not always accurately reflect a state in a body such as an amount of glycogen stored in a body and a level of glucose in blood at that time. In fact, the feeling of fullness tends to be easily obtained by increasing a number of times of chewing, and the feeling of hunger is not sensed during concentrating on a task. These show that the brain tends to be easily confused. Whereas, by measuring the level of glucose in the blood, it is possible to objectively understand the feeling of hunger. However, since this method involves collection of the blood, it is not easily performed by a typical individual. Thus, there is a need for a measure to objectively and easily understand the feeling of hunger and to find suitable timing for taking the meal.
Meanwhile, regarding exercise, doing exercise during fasting is more effective for the dieting. That is because the amount of glycogen stored in the body is small, and fat (e.g., visceral fat) tends to be easily burned. Further, regarding the exercise, quality and quantity of the exercise to be done is important. It is effective for the dieting to do exercise at proper exercise intensity that matches with an individual for a proper time period. There is an individual difference in endurance to the exercise. The fat does not burn when an exercise load is too large, or when the exercise load is too small.
Conventionally, it has been known that a fat-burning condition can be confirmed by measuring and analyzing components of biogas discharged from a living body. For example, Patent Document 1 discloses a method of confirming a burning condition of body fat by measuring an acetone level included in breathing gas. Further, Patent Document 2 discloses a method of calculating exercise intensity for efficiently burning the body fat by measuring an acetone level included in the breathing gas. Acetone is one of metabolic products associated with decomposition of the body fat. Though it is an infinitesimal quantity, acetone is included in the breathing gas and a gas component discharged from skin and a mucous membrane. Accordingly, acetone has a potential to be a marker for fat burning, which can be easily measured by an individual.
However, both Patent Document 1 and Patent Document 2 disclose nothing regarding a measure and a method for reporting suitable timing for taking the meal and suitable timing for doing exercise to an individual. Besides, these documents do not mention anything regarding a measure and a method for estimating a quantity of exercise in a predetermined time period and for advising an individual to improve lifestyle, so that a usual acetone concentration level is increased.